This invention relates to methods for the production of therapeutic dinucleotides including novel salts thereof. More specifically, it relates to methods for synthesis of P1, P4-di(uridine 5xe2x80x2)-tetraphosphate, i.e., diuridine tetraphosphate (U2P4) which have advantages over prior art methods of manufacture.
P1, P4-Di(uridine 5xe2x80x2)-tetraphosphate is a dinucleotide of the following structure: 
wherein:
X is Li, Na, K, NH4 or H, provided that all X groups are not H.
The free acid of P1, P4-di(uridine 5xe2x80x2)-tetraphosphate, where X is hydrogen, has been previously described as uridine 5xe2x80x2-(pentahydrogen tetraphosphate), Pxe2x80x2xe2x80x3xe2x86x925xe2x80x2-ester with uridine (CAS Registry Number: 59985-21-6; C. Vallejo et al., Biochimica et Biophysica Acta 438, 305 (1976) and H. Coste et al., J. Biol. Chem. 262, 12096 (1987)).
Different methods have been described for the synthesis of purine dinucleotides such as diadenosine tetraphosphate (A2P4) (E. Rappaport et al, Proc. Natl. Acad. Sci, 78, 838, (1981); A. Guranowski et al, Biochemistry, 27, 2959, (1988); C. Lobaton et al, Eur. J. Biochem., 50, 495, 1975; K. Ng and L. Orgel, Nucl. Acid Res., 15, 3573, (1987)). However, this has not been true for U2P4 which is a pyrimidine nucleotide. Although purine nucleotides and pyrimidine nucleotides appear to be analogous, the methods used for purine nucleotide synthesis do not necessarily work for pyrimidines such as uridine.
Diuridine tetraphosphate has been shown to have beneficial properties in the treatment of various diseases, such as chronic obstructive pulmonary disease (COPD). For example, they have been demonstrated to facilitate the clearance of mucous secretions from the lungs of a subject such as a mammal including humans in need of treatment for various reasons, including cystic fibrosis, chronic bronchitis, asthma, bronchiectasis, post-operative mucous retention, pneumonia, primary ciliary dyskinesia (M. J. Stutts, III, et al, U.S. Pat. No. 5,635,160; PCT International Publication WO 96/40059) and the prevention and treatment of pneumonia in immobilized patients (K. M. Jacobus and H. J. Leighton, U.S. Pat. No. 5,763,447). Further therapeutic uses include treatment of sinusitis (PCT International Publication WO 98/03177), otitis media (PCT International Publication WO 97/29756), dry eye, retinal detachment, nasolacrimal duct obstruction, the treatment of female infertility and irritation due to vaginal dryness via increased mucus secretions and hydration of the epithelial surface, and enhancing the performance of athletes.
U2P4 also has utility as a veterinary product in mammals such as, but not limited to, dogs, cats and horses.
Prior art methodology describes only one protocol for the production of diuridine tetraphosphate. This method is very time consuming, lasting over five days and producing only small amounts of diuridine tetraphosphate (C. Vallejo et al., Biochimica et Biophysica Acta 438, 305 (1976), Sillero et al., Eur J Biochem 76, 332 (1972)). According to this technique, diuridine tetraphosphate was synthesized through a reaction of uridine 5xe2x80x2-monophosphomorpholidate (0.54 mmol) with the triethylamine salt of pyrophosphoric acid (0.35 mmol) in a medium of anhydrous pyridine (10 ml). After 5 days at 30xc2x0 C., pyridine was removed from the reaction mixture by evaporation, and the residue resuspended in glass-distilled water (8 mL), the suspension applied to a DEAE-cellulose column (37.5xc3x972.6 cm) and fractionated with 3.2 L of a linear gradient (0.06-0.25 M) of ammonium bicarbonate, pH 8.6. The peak eluting between 0.17-0.19 M ammonium bicarbonate was partially characterized as U2P4 by the following criteria: insensitivity to alkaline phosphatase, phosphorus to base ratio and analysis of the products of hydrolysis (UTP+UMP), after treatment with phosphodiesterase I, by electrophoresis in citrate buffer, pH 5.0. No yield or spectroscopic data were given. Thus, the prior art procedure for the synthesis of diuridine tetraphosphate is lengthy and produced only small amounts of only partially characterized diuridine tetraphosphate. The present invention focuses on methods to produce this medically useful compound which may be more efficiently and conveniently carried out, and which may be applied to the large-scale production of diuridine tetraphosphate and salts thereof.
The present invention provides new methods for the synthesis of the therapeutic dinucleotide, P1, P4-di(uridine 5xe2x80x2)-tetraphosphate (Formula I), and demonstrates applicability to the production of large quantities. The methods of the present invention substantially reduce the time required to synthesize diuridine tetraphosphate, preferably to three days or less. The ammonium, sodium, lithium, and potassium salts of P1, P4-di(uridine 5xe2x80x2)-tetraphosphate prepared by these methods are stable, soluble, nontoxic, and easy to handle during manufacture. The tetrasodium, tetraammonium, tetralithium and tetrapotassium salts of P1, P4-di(uridine 5xe2x80x2)-tetraphosphate (Formula I) prepared by these methods are highly pure and stable. 
wherein:
X is Na, NH4, Li, K, or H, provided that all X groups are not H.
The method of synthesizing compounds of Formula I, and pharmaceutically acceptable salts thereof, is carried out generally by the following steps: 1) dissolving uridine or uridine nucleotide compounds of Formulas IIa-d in a polar, aprotic organic solvent and a hydrophobic amine; 2) phosphorylating with a phosphorylating agent of one of the Formulas IVa-b to yield a compound of Formula I, or activating a phosphate group of the uridine nucleotide compound with an activating agent of one of the Formulas IIIa-c and reacting with a suitable compound of Formula II b-d to yield a compound of Formula I; and 3) purifying by ion exchange chromatography.
Another aspect of the present invention are methods of treating various disease states, including, but not limited to: chronic obstructive pulmonary diseases, sinusitis, otitis media, nasolacrimal duct obstruction, dry eye disease, retinal detachment, pneumonia, and female infertility or irritation caused by vaginal dryness.
Another aspect of the present invention is a pharmaceutical composition comprising a compound of Formula I together with a pharmaceutically acceptable carrier.
The present invention provides new methods for the synthesis of the therapeutic dinucleotide, P1, P4-di(uridine 5xe2x80x2)-tetraphosphate, and demonstrates applicability to the production of large quantities. The methods of the present invention substantially reduce the time period required to synthesize P1, P4-di(uridine 5xe2x80x2)-tetraphosphate, preferably to three days or less. The ammonium, potassium, lithium and sodium salts of P1, P4-di(uridine 5xe2x80x2)-tetraphosphate (Formula I) prepared by these methods are stable, soluble, nontoxic, and easy to handle during manufacture.
The present invention further provides compounds of Formula I: 
wherein:
X is Na, NH4, Li, K, or H, provided that all X groups are not H.
The sodium, ammonium, lithium and potassium salts of P1, P4-di(uridine 5xe2x80x2) -tetraphosphate have many advantages, for example, they provide good long-term stability profiles compared to those of divalent cations (e.g. Ca2+, Mg2+, Mn2+) which catalyze hydrolysis of phosphate esters.
These inorganic sodium, ammonium, lithium, and potassium salts impart excellent water solubility compared to hydrophobic amine salts such as tri- and tetrabutylammonium, and similar salts. High water solubility is an important advantage for flexibility in pharmaceutical formulations of varying concentration.
The tetrammonium, tetrasodium, tetralithium and tetrapotassium salts of P1, P4-di(uridine 5xe2x80x2)-tetraphosphate are additionally advantageous in that they are readily purified by aqueous ion chromatography in which no organic solvents are used. They have high degree ( greater than 90%) of purity, thus are suitable for pharmaceutical use. These tetraammonium and tetra monovalent alkali metal salts are more resistant to hydrolysis than the mono-, di-, or tri- salts, therefore, they provide an improved stability and a longer shelf life for storage. In addition, these salts are easily handled as fluffy, white solids, compared to an oil or gum as with some amine salts.
The tetrasodium, tetralithium, and tetrapotassium salts of P1, P4-di(uridine 5xe2x80x2) -tetraphosphate are non-irritating to the lung and eyes. Other cations may be irritating to the lungs, eyes, and other mucosal epithelia, or are otherwise not well tolerated by the human body. The tetrasodium, tetralithium, and tetrapotassium salts are preferred.
The compounds of Formula I may be used to facilitate the clearance of mucous secretions from the lungs of a subject such as a mammal including humans in need of treatment for various reasons, including cystic fibrosis, chronic bronchitis, asthma, bronchiectasis, post-operative mucous retention, pneumonia, primary ciliary dyskinesia (M. J. Stutts, III, et al, U.S. Pat. No. 5,635,160; PCT International Publication WO 96/40059) and the prevention and treatment of pneumonia in immobilized patients (K. M. Jacobus and H. J. Leighton, U.S. Pat. No. 5,763,447). Further therapeutic uses include treatment of sinusitis (PCT International Publication WO 98/03177), otitis media (PCT International Publication WO 97/29756), dry eye, retinal detachment, nasolacrimal duct obstruction, the treatment of female infertility and irritation due to vaginal dryness via increased mucus secretions and hydration of the epithelial surface, and enhancing the performance of athletes.
The compounds of Formula I may be administered orally, topically, parenterally, by inhalation or spray, intra-operatively, rectally, or vaginally in dosage unit formulations containing conventional non-toxic pharmaceutically acceptable carriers, adjuvants and vehicles. The term topically as used herein includes patches, gels, creams, ointments, suppositiories, pessaries, or nose, ear or eye drops. The term parenteral as used herein includes subcutaneous injections, intravenous, intramuscular, intrasternal injection or infusion techniques. In addition, there is provided a pharmaceutical formulation comprising a compound of general Formula I and a pharmaceutically acceptable carrier. One or more compounds of general Formula I may be present in association with one or more non-toxic pharmaceutically acceptable carriers or diluents or adjuvants and, if desired, other active ingredients. One such carrier would be sugars, where the compounds may be intimately incorporated in the matrix through glassification or simply admixed with the carrier (e.g., lactose, sucrose, trehalose, mannitol) or other acceptable excipients for lung or airway delivery.
One or more compounds of general Formula I may be administered separately or together, or separately or together with: mucolytics such as DNAse (Pulmozyme(copyright)) or acetylcysteine, antibiotics, including but not limited to inhaled Tobramycin(copyright); non-steroidal anti-inflammatories, antivirals, vaccines, decongestants and corticosteroids.
The pharmaceutical compositions containing compounds of general Formula I may be in a form suitable for oral use, for example, as tablets, caplets, lozenges, aqueous or oily suspensions, dispersible powders or granules, emulsion, hard or soft capsules, or syrups or elixirs. Compositions intended for oral use may be prepared according to any method known to the art for the manufacture of pharmaceutical compositions and such compositions may contain one or more agents selected from the group consisting of sweetening agents, flavoring agents, coloring agents and preserving agents in order to provide pharmaceutically elegant and palatable preparations. Tablets contain the active ingredient in admixture with non-toxic pharmaceutically acceptable excipients which are suitable for the manufacture of tablets. These excipients may be, for example, inert diluents, such as calcium carbonate, sodium carbonate, lactose, calcium phosphate or sodium phosphate; granulating and disintegrating agents, for example, corn starch, or alginic acid; binding agents, for example, starch, gelatin or acacia; and lubricating agents, for example magnesium stearate, stearic acid or talc. The tablets may be uncoated or they may be coated by known techniques to delay disintegration and absorption in the gastrointestinal tract and thereby provide a sustained action over a longer period. For example, a time delay material such as glyceryl monostearate or glyceryl distearate may be employed.
Formulations for oral use may also be presented as hard gelatin capsules wherein the active ingredient is mixed with an inert solid diluent, for example, calcium carbonate, calcium phosphate or kaolin, or as soft gelatin capsules wherein the active ingredients is mixed with water or an oil medium, for example, peanut oil, liquid paraffin or olive oil.
Aqueous suspensions contain the active materials in admixture with excipients suitable for the manufacture of aqueous suspensions. Such excipients are suspending agents, for example: sodium carboxymethylcellulose, methylcellulose and sodium alginate. Dispersing or wetting agents may be a naturally-occurring phosphatide or condensation products of an allylene oxide with fatty acids, or condensation products of ethylene oxide with long chain aliphatic alcohols, or condensation products of ethylene oxide with partial esters from fatty acids and a hexitol, or condensation products of ethylene oxide with partial esters derived from fatty acids and hexitol anhydrides. Those skilled in the art will recognize the many specific excipients and wetting agents encompassed by the general description above. The aqueous suspensions may also contain one or more preservatives, for example, ethyl, or n-propyl p-hydroxybenzoate, one or more coloring agents, one or more flavoring agents, and one or more sweetening agents, such as sucrose or saccharin.
Dispersible powders and granules suitable for preparation of an aqueous suspension by the addition of water provide the active ingredients in admixture with a dispersing or wetting agent, suspending agent and one or more preservatives. Suitable dispersing or wetting agents and suspending agents are exemplified by those already mentioned above. Additional excipients, for example, sweetening, flavoring, and coloring agents, may also be present.
Compounds of Formula I may be administered parenterally in a sterile medium. The drug, depending on the vehicle and concentration used, can either be suspended or dissolved in the vehicle. Advantageously, adjuvants such as local anaesthetics, preservatives and buffering agents can be dissolved in the vehicle. The sterile injectable preparation may be a sterile injectable solution or suspension in a non-toxic parentally acceptable diluent or solvent. Among the acceptable vehicles and solvents that may be employed are sterile water, saline solution, or Ringer""s solution. The compounds of general Formula I may also be administered in the form of suppositories for ear, rectal or vaginal administration of the drug. These compositions can be prepared by mixing the drug with a suitable non-irritating excipient which is solid at ordinary temperatures but liquid at the body temperature and will therefore melt to release the drug. Such materials are cocoa butter and polyethylene glycols.
Solutions of compounds of Formula I may be administered by intra-operative installation at any site in the body.
Single dosage levels of the order of from about 1 to about 400 mg, preferably in the range of 10 to 300 mg, and most preferably in the range of 25 to 250 mg, are useful in the treatment of the above-indicated respiratory conditions. Single dosage levels of the order of from about 0.0005 to about 5 mg, preferably in the range of 0.001 to 3 mg and most preferably in the range of 0.025 to 1 mg, are useful in the treatment of the above-indicated ophthalmic conditions. The amount of active ingredient that may be combined with the carrier materials to produce a single dosage form will vary depending upon the host treated and the particular mode of administration. It will be understood, however, that the specific dose level for any particular patient will depend upon a variety of factors including the activity of the specific compound employed, the age, body weight, general health, sex, diet, time of administration, route of administration, and rate of excretion, drug combination and the severity of the particular disease undergoing therapy.
The synthetic methods described below encompass several synthetic strategies for producing P1, P4-di(uridine 5xe2x80x2)-tetraphosphate. Generally, all the methods use uridine or uridine nucleotide compounds from Formula Ila-d as starting materials, which are dissolved in a polar, aprotic organic solvent (e.g. dimethylformamide, dimethylsulfoxide, dioxane, N-methylpyrrolidone, trimethylphosphate) and a hydrophobic amine (e.g. triethylamine, tributylamine, trioctylamine, 2,4,6-collidine, tetrabutylammonium, tri- and tetra-alkyl amines, heterocyclic amines). The product is obtained by phosphorylating with a phosphorylating agent from Formula IV (e.g. phosphorus oxychloride, pyrophosphate, pyrophosphorylchloride) or activating a phosphate group with an activating agent from Formula III (e.g. carbonyldiimidazole, an alky or aryl carbodiimide, an alkyl or aryl phosphochloridate), respectively, with subsequent purification various means well known to those of skill in the art, including, but not limited to, ion chromatography (e.g. DEAE Sephadex, DEAE cellulose, Dowex 50, anion and cation exchange resins).
The pyrimidine xcex2-D-ribofuranosyl starting materials uridine, uridine 5xe2x80x2-monophosphate (UMP), uridine 5xe2x80x2-diphosphate (UDP), and uridine 5xe2x80x2-triphosphate (UTP) are shown as free acids in Formulas IIa-d below, respectively. These materials are all commercially available in large quantity in various salt forms. 
and salts thereof; 
and salts thereof; 
and salts thereof.
The activating agents carbodiimide, activated carbonyl, and activated phosphorus compounds are shown in the general Formulas IIIa-c below, respectively. 
wherein R1and R2 are C1-C8 alkyl or cycloalkyl, C1-C8 optionally substituted alkyl or cycloalkyl(e.g. hydroxy and amino groups); aryl or optionally substituted aryl (e.g. hydroxy and amino groups). Preferred compounds of Formula IIIa are dicyclohexylcarbodiimide and 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride. 
wherein X is imidazole, tetrazole, and/or halogen. Preferred compounds of Formula IIIb are carbonyldiimidazole and carbonylditriazole. 
wherein R1 and R2 are C1-C8 alkyl or cycloalkyl, C1-C8 optionally substituted alkyl, alkoxy or cycloalkyl (e.g. hydroxy and amino groups); aryl, alkoxy or optionally substituted aryl or alkoxy (e.g. hydroxy and amino groups) and/or halogen; and X is halogen. Preferred compounds of Formula IIIc are diphenylphosphorochloridate, phenyl phosphorodichloridate, phenylphosphonic dichloride and diphenylphosphinic chloride.
The mono- and diphosphorylating agents are shown below in the general formulas IVa-b. 
wherein X is halogen. Preferred compound of Formula IVa is phosphorus oxychloride. 
wherein X is oxygen, hydroxy, or halogen, and salts thereof. Preferred compounds of Formula IVb are pyrophosphoryl chloride and pyrophosphate.
Those having skill in the art will recognize that the present invention is not limited to the following examples and that the steps in the following examples may be varied.